We discuss in this proposal the use of tunable laser resonance Raman spectroscopy to study rhodopsin membranes. Such membranes may retain the physiological properties of the disc membranes from the photoreceptor cells of the rod outer segment, and may therefore be functional models of the primary receptor membranes in the visual system. Resonance Raman spectroscopy can then be used to reveal specific molecular changes occurring in these membranes when thy interact with light. Measurements of ionic transport through these membranes may be possible by spectroscopically monitoring ionic probes which are trapped in vesicles formed from the rhodopsin membranes. Using such techniques, we propose to relate structural changes in rhodopsin lipid bilayers to changes in the ionic permeability of these membranes. By using photoexcitation and temperature changes to induce changes in the rhodopsin lipid bilayer, we may be able to gain insights into the role of rhodopsin in mediating transport across membranes.